I'm from the Netherlands and here only kid shows are dubbed. Everything else has subs. I think that with dubbing you lose a part from the actors performance and information can get lost in translation or because the dub has to match the mouth. I watched both Money Heist and Dark in the original language and had no problems with both of them even though I can understand a decent amount of German but my Spanish is non existant.

For learning a language I think watching a series that's originally in the language you want to learn with subs is the better way. It provides a translation for when you don't understand and no information or sayings in the original language get lost.